ABSTRACT
Psychosis is one of the most dramatic and evident expressions of mental illness, frequently obscuring less colorful manifestations, such as negative symptoms (see the “Negative Symptoms” chapter). When it comes to whether psychosis is structured continuously or discretely, there are two main overlapping foci: Th e extension of psychosis to the general population, and the process/structure of psychotic symptoms. Substantial research eff orts have been directed at determining if psychosis is continuous between the non-clinical and clinical populations, and much of this research focuses on auditory hallucinations. Depending on the methods employed and group studied, the prevalence of auditory hallucinations can range from nearly zero to very high (Beavan et al, 2011; Linscott & Van Os, 2010; Kelleher et al, 2012). For instance, Beavan et al (2011) reported on 17 surveys from nine countries, conducted over an extensive period (from the late 19th to early 21st century), that showed a range of verbal auditory hallucination from 0.6% to 84%, the diff erences due to various defi nitions, methodologies, and cultural factors. A more extensive cross-cultural review involving data from 52 countries produced a fi gure of 5.8%, with a substantial range from near zero to 31.4% in Nepal (Linscott & Van Os, 2010). Th e prevalence of auditory verbal hallucinations appears to be somewhat higher in children and adolescents, with one study fi nding 14.8% (Kelleher et al, 2012).
